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Full text of "Text Book Of Mechanical Engineering"

16

Bend in Loam.

example. To mould it we may either

have a complete pattern and core

box, when it would be done in

green sand, and  needs  no

further explanation; or it

may be worked in loam

by the aid of tem-
plates.    For the

latter method we

may  proceed   in

the following manner:
Take an iron plate,

Fig. 25, and on it fasten
the bent wire A of square
section as a guide for the
template B. Loam being laid,
it is traced out by B, which
gives it the form of the internal
surface. The length of the bend is
carefully measured off at c and D,
care being taken to allow an extra
piece at D to support the core, while at c
is applied the core box, E, giving the shape
of the internal faucet; the core is then care-
fully dried and black washed. Now apply more
loam and trace out by means of the larger
template G, which gives the necessary thickness,
while the faucet is supplied by the impression
of the core box H, and the spigot by that of j. The added
thickness is sbown by the dotted lines. Drying and black-
washing are again performed. Lastly, cover the whole plate
with loam, which, as it is required to be lifted off entire, must
be well stayed with cross and longitudinal wires tied together
by small wire. A wire should also stiffen the internal cores.
(The whole of the foregoing is repeated opposite hand, on the
plate F, the same bent wire being used.)

The solid block of loam thus formed on either board is
taken off, dried and blackwashed, and now all is ready for putting